机电安装技术在大跨度玻璃穹顶建筑工程中的应用

北京某文旅项目201单体为造型复杂的大跨度玻璃穹顶建筑,其机电管线和灯具在穹顶水平环梁和主拱梁上安装难度极大.经研究采用综合支架、合理规划路由等措施,满足了设计和使用要求.     

Ab initio study of helium in Li4SiO4 crystals: Electronic properties,migration, and vacancy capture mechanism

Li₄SiO₄ crystal is a candidate material for tritium breeder material. Vacancy defects and He atoms will be produced in the crystal after neutron irradiation in fusion reactor. In previous research, we learned vacancy defects mainly include V_O⁰, V_O²⁺, and V_Li⁰, meanwhile, He atoms are easy to migrate and aggregate in the crystal. In order to understand the relationship between vacancy defects and He atoms, we use density functional theory (DFT) to study the interaction mechanism between vacancy and He atom. The results show that the local stable sites of He atoms are related to the surrounding charge distribution. V_O²⁺ and V_Li⁰ can capture interstitial He atoms, and it is difficult to escape the vacancies, thereby increasing the nucleation center of He atoms. V_O⁰ promotes the diffusion of He atoms in the interstitial space, which will cause small helium bubbles to merge more easily.     

拉索检测爬升装置轻量化设计与动力学性能分析

斜拉桥的自动化、智能化检测是今后的发展趋势,目前已研发的拉索检测机器人都存在质量较大的问题,很难得到工程实际应用.针对课题组前期研制的第一代爬升装置样机质量大、爬升速度较慢等问题,对其进行了受力分析与静应力分析,得出了优化的可能性.提出了零件板厚为优化参数,强度变化率为约束条件的尺寸优化模型,利用差分进化算法求取最优解,得到了机架的最优板厚,同时通过拓扑优化得到各零件最佳结构,以及通过受力分析对螺栓的尺寸与数量进行了优化.优化结果表明爬升装置减重3.9kg,减重比例达到了40％,同时机架的变形量大幅减小,强度满足要求.对优化后的爬升装置进行了动力学仿真分析,结果表明最大爬升角度达到了75度,爬升速度提升了2-4倍,其动力性得到极大的改善.     

复合材料控制臂的多区域铺层结构优化

使用碳纤维复合材料设计某乘用车悬架控制臂,对4个区域的铺层结构进行优化设计.首先以各角度铺层厚度为设计变量对控制臂模态频率、质量和各工况应变能进行优化;然后以前三阶模态频率为目标,弯曲刚度参数作为设计变量优化铺层顺序.针对设计变量间存在的工艺约束条件使样本空间不规则且优化变量较多的问题,利用聚类分析进行试验设计确定训练近似模型需要的样本点,并用高斯过程回归方法建立近似模型以减少计算时间,验证模型R2在0.9以上.两步优化后,对比复合材料初始铺层各性能指标均有不同程度改善,复合材料质量减少11.4％;对比原钢制控制臂,各性能均满足要求,质量降低37.1％.     

建筑用夹层玻璃常见质量问题及原因分析

阐述了建筑用夹层玻璃产品检测中一些常见的质量问题,对其产生的原因进行分析,并对建筑用夹层玻璃的生产和质量管理提出建议.     

Ni1−xCoxSe2?C/ZnIn2S4 Hybrid Nanocages with Strong 2D/2D Hetero-Interface Interaction Enable Efficient H2-Releasing Photocatalysis

Designing a semiconductor-based heterostructure photocatalyst for achieving the efficient separation of photogenerated electron-hole pairs is highly important for enhancing H₂ releasing photocatalysis. Here, a new class of Ni_1−xCo_xSe₂–C/ZnIn₂S₄ hierarchical nanocages with abundant and compact ZnIn₂S₄ nanosheets/Ni_1−xCo_xSe₂^ C nanosheets 2D/2D hetero–interfaces, is designed and synthesized. The constructed heterostructure photocatalyst exposes rich hetero-junctions, supplying the broad and short transfer paths for charge carriers. The close contacts of these two kinds of nanosheets induce a strong interaction between ZnIn₂S₄ and Ni_1−xCo_xSe₂ C, improving the separation and transfer of photo-generated electron-hole pairs. As a consequence, the distinctive Ni_1−xCo_xSe₂ C/ZnIn₂S₄ hierarchical nanocages without using additional noble-metal cocatalysts, display remarkable H₂-relaesing photocatalytic activity with a rate of 5.10 mmol g⁻¹ h⁻¹ under visible light irradiation, which is 6.2 and 30 times higher than those of fresh ZnIn₂S₄ nanosheets and bare Ni_1−xCo_xSe₂ C nanocages, respectively. Spectroscopic characterizations and theory calculations reveal that the strong interaction between ZnIn₂S₄ and Ni_1−xCo_xSe₂ C 2D/2D hetero-interfaces can powerfully promote the separation of photo-generated charge carriers and the electrons transfer from ZnIn₂S₄ to Ni_1−xCo_xSe₂ C.     

梯度铝蜂窝夹芯板的力学行为

梯度分层铝合金蜂窝板是一种有效的吸能结构,本工作在梯度铝蜂窝结构的基础上根据梯度率的概念,通过改变蜂窝芯层的胞壁长度,设计了4种质量相同、梯度率不同的铝蜂窝夹芯结构。通过准静态压缩实验,并结合非线性有限元模拟准静态及冲击态下梯度铝蜂窝夹芯结构的变形情况及其力学性能,分析对比了相同质量下梯度铝蜂窝夹芯结构在准静态下的变形模式以及冲击载荷下分层均质蜂窝结构和不同梯度率的分层梯度蜂窝结构的动态响应和能量吸收特性。结果表明:在准静态压缩过程中,铝蜂窝梯度夹芯板的变形具有明显的局部化特征,蜂窝芯的变形为低密度优先变形直至密实,层级之间的密实化应变差随芯层密度的增大而逐渐减小;在高速冲击下,梯度蜂窝板并非严格按照准静态过程中逐级变形直至密实,而是在锤头冲击惯性及芯层密度的相互作用下整体发生的线弹性变形、弹性屈曲、塑性坍塌及密实化;另外,在本工作所设计的梯度率中,当梯度率为γ₁=0.0276时,梯度蜂窝夹芯板的吸能性达到最好,相较于同等质量下的均质蜂窝夹芯板,能量吸收提高了10.63%。